(adj). 1. An occurrence that happens without human influence, automatic, specifically not triggered by the speaker, that also contains an element of uncertainty or surprise. 2. An occurrence, or series of occurrences, triggered by a person who does not pre-plan the action(s) either at all or sufficiently. (Implies deficiency.)

1) Lightning was striking randomatically all over the place.
2) My computer keeps getting viruses randomatically.
3) (In a video game) They were just casting spells randomatically.
4) Try throwing the rope to the person, not just randomatically all over the lake!